Field of Invention
This invention relates generally to a method for the reprocessing of a contaminated device having internal passageways before such a device is reused in a clean environment. The term “reprocessing,” as used herein constitutes the washing, disinfecting, sterilizing and/or pasteurizing of such a device. The term “device” as used herein constitutes any devices having internal passageways that require such reprocessing, including, but not limited to, medical instruments and medical devices. The terms “medical instrument” and “medical device” are understood to constitute devices having one passageway or a plurality of passageways, including, but not limited to endoscopes, colonoscopes, and other flexible and rigid medical instruments.
Some automated systems for reprocessing devices having internal passageways for reuse are generally available and are commonly relied upon. For example, systems for reprocessing medical instruments having passageways are used by hospitals to safeguard patients and hospitals employees from exposure to infection and cross-contamination. Such prior art reprocessing units are manufactured by several different companies including, Custom Ultrasonics, Inc., of Ivyland, Pa., the assignee of the present invention and application. For example there are reprocessing units in the prior art adapted for cleaning, disinfecting and sterilizing flexible scopes, e.g., upper and lower gastrointestinal scopes, colonoscopes and duodescopes.
Prior art reprocessing systems, suitable in particular for reprocessing medical instruments, operate in accordance with a predetermined protocol of reprocessing steps. The protocol is based upon the specific cleaning requirements of the particular instruments being cleaned. The reprocessing steps are precisely timed and sequenced in order to assure optimal results, based upon the correct combination of water temperature, detergent and chemical agents. Thus, parameters such as wash and rinse cycle time, chemical immersion cycle time and water temperature and pressure were preset by the reprocessing unit manufacturer and could not be altered by an end user of the system. U.S. Pat. No. 5,761,069, issued to Weber, et. al. teaches a system for cleaning medical instruments having a database of protocols corresponding to differing medical instruments for permitting a user to load and execute the protocol corresponding to the instrument being reprocessed.
An exemplary protocol for cleaning a medical instrument could include the following reprocessing steps, after the instrument has been placed in the cleaning basin of the reprocessing unit: (1) wash the internal and external surfaces of the instrument with a measured detergent-water mixture for a preset period of time; (2) activate ultrasonic crystals while washing; (3) drain the detergent-water mixture after the wash cycle is completed; (4) after draining, rinse the internal and external surfaces of the instrument with water at a preset temperature for a preset period of time; (5) introduce and circulate disinfectant over and through the instrument for a preset period of time; (6) drain the disinfectant from the wash basin; and (7) after draining of the disinfectant is complete, rinse the instrument with water; and (8) re-rinse the instrument with water.
Prior art reprocessing units adapted, in particular, for reprocessing medical equipment, typically comprise a variety of mechanical components, e.g., pumps, tubes, solenoid valves, ultrasonic transducers, heaters and probes that perform the various reprocessing steps. The pumps used in these units must be very precise and reliable over extended periods of time. Thus, pumps that are suitable for these units can be quite expensive.
In many cases it is necessary to reprocess devices having passageways of differing diameters. The differing diameters can occur in a single device having passageways of differing diameters, or in multiple devices, each having a single differing diameter. The presence of differing diameter passageways creates a need for fluid flows of corresponding differing pressures, because more narrow passageways require a higher pressure to force fluid therethrough. Prior art reprocessing units suitable for reprocessing devices having passageways of differing diameters included a plurality of pumps and associated tubing systems, wherein each pump provided one of the differing pressures required to reprocess the differing passageways of the devices.
Furthermore, some devices can have extremely narrow passageways, requiring dedicated high-pressure pumps that are capable of providing extremely high pressures. Pumps for such extremely narrow, high-pressure passageways have very low flow rates. Flow rates that are this low are difficult to monitor. For example, the flow rates of fluids through the passageways of some devices can be on the order of a drop a minute. Passageways this narrow can be found, for example, in flexible medical instruments, such as endoscopes.
Known reprocessing units are typically equipped with a pressure sensor for measuring the overall flow of fluid through the pump for the purpose of detecting obstructions in the passageways of the devices. However, is possible for an obstruction preventing flow of in one of the passageways to go undetected by the pressure sensor since the flow can continue through the remaining passageways and only the overall pressure of the liquid is determined.
Several governmental and independent agencies have issued guidelines for reprocessing particular types of medical instruments. For example, such guidelines often require that certain types of medical instruments be washed and sterilized using a chemical disinfectant, while other types of instruments need only be washed. The design of reprocessing units and the reprocessing steps they perform must conform to such guidelines. Additionally, guidelines have been created to reliably prevent instruments from being reused if an obstruction occurs in a single passageway of a plurality of passageways during reprocessing. Prior art reprocessing units are not reliably able to meet these guidelines.